An apparatus for developing a latent charge image on a photoreceptor that is disposed on an interior surface of a viewing faceplate of a display device, such as a cathode-ray tube (CRT), using triboelectrically charged particles, is described in U.S. Pat. No. 5,477,285, issued on Dec. 19, 1995, to G. H. N. Riddle et al. In a first embodiment of the developing apparatus, a developing chamber having insulating sidewalls and an insulative panel support is described. A triboelectric gun for directing charged screen structure material onto a photoreceptor provided on the interior surface of the CRT faceplate panel is disposed within the developing chamber. A drawback of the developing chamber is that the electrostatically charged screen structure material creates a charge buildup on the insulating sidewalls. The electrostatic forces from the sidewalls are not well controlled and the forces vary as the charge varies. For example, when the developing chamber is cleaned, to remove excess screen structure materials from the sidewalls, the electrostatic charge decreases. The electrostatic forces also vary when the humidity changes. Variations of 500 to 5000 volts have been recorded in the measured electrostatic fields of an operating developing chamber. In another embodiment of a developing chamber described in the above-referenced U.S. Pat. No. 5,477,285, an interior chamber of conductive material, comprising a sidewall and a bottom, is disposed within the developing chamber. The conductive interior chamber is electrically floating and attracts excess screen structure material out of the powder cloud generated within the chamber by the triboelectric gun, thereby preventing both a buildup of space charge within the chamber and a high electrostatic potential on the chamber wall. However, it has been determined that the screen structure material builds up on the conductive sidewall of the inner chamber in the form of "snow banks" of agglomerated particles, which may give rise to large agglomerated particles on the screen if the particles become dislodged from the sidewall. Thus, it is desirable that the drawbacks of the prior developing apparatus be addressed and eliminated.